Application Note
Laboratory Density & Concentration Measurement

1. Introduction outstanding performance at a very attractive price – the Anton Paar Alcolyzer

[ ii
].
Wine is an alcoholic beverage resulting from the fermentation of grape juice by yeasts with appropriate processing and addition.
2. Traditional alcohol determination by distillation
The main components of wine are water and ethanol. The components of next abundance are sugars (mainly glucose and fructose), acids, other alcohols, and phenolics all being present in the magnitude of grams per liter. In addition wine contains another 500 additional nonvolatile and volatile chemicals in trace amounts (aroma and color compounds, …).
The alcohol content of alcohol/water mixtures can be determined by density measurement followed by conversion into alcohol concentration using official alcohol tables.
Beside alcohol and water, wine contains extract which influences the density. Therefore direct alcohol determination using density measurement is impossible.
Accurate alcohol content determination of wines is very important for wine making, blending, trading and even consuming. The knowledge of the alcohol content is necessary to ensure that the wine conforms to the label declaration of alcohol content, and to establish the basis for the payment of tax.
The wine has to be separated into an alcohol and an extract fraction by performing a
distillation.
The distillation analysis is usually performed according to national or international standard methods [ iii
].
The officially recognized method for the determination of alcohol concentrations in wine is distillation. It is a time consuming procedure and requires experienced operators. The same holds true for alcohol determination by gas chromatography. Simpler methods like combined density/refractive index method and boiling point determination (ebulliometry) are less accurate.
Generally distillation is performed as follows:
A precisely measured volume (or weight) of the wine is filled into a suitable distillation apparatus.
The wine is neutralized with calcium hydroxide or sodium hydroxide solution to avoid evaporation of volatile acids. Then the distillation is performed, and the obtained alcohol fraction is filled up to the original volume (or weight) with distilled water.
Present near infrared (NIR) spectroscopy based methods are fast and accurate, but suffer from the need for elaborate calibrations, the limited applicability of these calibrations and the high price of the corresponding instruments.
A new, patented method [ i
] from Anton Paar of using NIR spectroscopy to determine the alcohol content in wine avoids the shortcomings of present NIR based systems. Its application led to an NIR based dedicated alcohol analyzer offering simple calibration, simple operation and
This liquid now is of the identical alcoholic strength as the original sample, but it does not contain extract any more. The alcohol concentration in e.g. %volume (%v/v) or %weight
(%w/w) is determined with high precision using density measurement and an appropriate concentration table, see also [ iv
].
Anton Paar
GmbH
Anton-Paar-Str. 20, A-8054 Graz, Austria – Europe
Tel: +43 316 257-0, Fax: +43 316 257-257
E-mail: info@anton-paar.com
Web: www.anton-paar.com
Instruments for: Density and concentration measurement
Rheometry and viscometry
Sample preparation
X-ray structure analysis
Microhardness testing
High-precision temperature measurement
CO
2
measurement
Colloid science
Page 1 of 9
XDLIA48A.doc

Application Note
Alcohol Measurement in Wine Using the Alcolyzer
3. Alcohol determination with the NEW
Alcolyzer

The Alcolyzer

by Anton Paar is based on a new approach of using NIR spectroscopy for the alcohol determination in wine.
Influences of other sample components on the spectrum are virtually eliminated by using a small, highly alcohol specific spectral range combined with a powerful evaluation algorithm.
This results in a small error (< 0.1 %v/v) and an outstanding repeatability (0.015 %v/v) of the determined alcohol content in the range of 0 to
20 %v/v.
The Alcolyzer

measures the alcohol content in wine in %v/v. By optional combination with a density meter, the Alcolyzer

can also display the alcohol content in %w/w, density, specific gravity and total extract.
Operation of the Alcolyzer

For best performance the Alcolyzer

should be turned on all the time.
Sample handling
Sample preparation other than degassing of samples with a strong tendency to form bubbles or filtering of very turbid samples is not necessary.
Special care must be taken at any step to prevent any evaporation of alcohol. The sample containers have always to be covered. The loss of alcohol from uncovered containers can amount up to several hundredths of a percent
within a few minutes.
The use of sample containers which are not filled completely (e.g. half-empty bottles) can result in wrong results even if they have been covered.
The alcohol tends to evaporate into the head space above the liquid, and the sample itself changes its composition. To restore the original composition, gently tilt the flask repeatedly (do not shake!) to dissolve all the alcohol in the sample again, and immediately perform the measurement.
XDLIA48A.doc
Filling
The Alcolyzer

can either be filled by syringe, peristaltic pump or automatic sample changer
SP-1m or SP-3m.
Manual filling by syringe
Plastic syringes with a standard Luer-tip and 5 ml volume can be used to fill the samples into the measuring cell. The sample should always be filled through the lower adapter. About two thirds of the sample should be pushed slowly through the measuring cell. The syringe must remain in the filling nozzle during the measurement.
If the measuring cell is clean and dry, 3 ml of sample is sufficient. If the previous sample has to be replaced by the new one, at least 10 ml of sample is needed
Filling by peristaltic pump
The pump should be able to handle 10 to 30 ml of sample per minute. The pump must be turned off during the measurement. If one sample is displaced by the following sample, a minimum of
20 ml has to be pumped through the measuring cell and hoses to prevent contaminations of the sample with the previous ones.
Automatic filling by sample changer
SP-1m/SP-3m
24 to 60 samples are automatically filled and measured. Several filling modes can be used.
Measuring and cleaning
Temperature control to 20 °C of the sample is automatically performed in the instrument by a
Peltier thermostat.
The measuring time is approximately one minute, whereby most of the time is required for sample filling and attemperating.
If no measurements are performed for extended periods of time (overnight, over the weekend) the measuring cell should be cleaned and dried carefully to avoid contamination (e.g. algae buildup).
The cleaning is best done by rinsing with distilled water immediately after the last sample. After rinsing with pure ethanol (without denaturant) the measuring cell should be dried using the built-in air pump.
Page 2 of 9

Application Note
Alcohol Measurement in Wine Using the Alcolyzer
Regular cleaning with a standard lab cleaner
(e.g. RBS

or Mucasol

) will help to prevent the formation of deposits in the measuring cell.
Adjustment
The Alcolyzer

by Anton Paar is simply adjusted with bidistilled degassed water for the zero percent alcohol concentration, and a binary ethanol water mixture of known concentration.
No elaborate calibrations are required as for other NIR instruments.
The validity of the adjustment should be checked regularly (at best once a day) by measuring bidistilled, degassed water. If the displayed value is 0
±
0.02 %v/v and is stable for a few minutes, measurements can be performed.
If the displayed value is out of this concentration range, the measuring cell has to be cleaned and dried.
Another control measurement should be performed; if the measuring result is still out of range (0
±
0.02 %v/v) perform a zero point adjustment.
Measuring results
The performance of the Alcolyzer

was compared to other methods of alcohol determination by different laboratories specialized on wine analysis.
Alcolyzer
 compared to distillation
Test measurements with the Alcolyzer

were performed at different places. Among them was
1
Unione Italiana Vini (Verona, Italy) [ ], an independent wine laboratory, that has compared the Alcolyzer

results to distillation.
From 135 measurements the average deviation of the Alcolyzer from distillation was found to be smaller than 0.02 %v/v and the repeatability was
±
0.015 %v/v.
Some representative measuring results are shown in table 1.
In the last column the content of reducing sugars
(mainly glucose and fructose) is listed. It was determined by titration, alternatively the sugar content can be determined by a wet chemical
[
1
] Unione Italiana Vini, Dr. Pavanello, Viale del
Lavoro 8, Verona, Italy
XDLIA48A.doc
reduction of CuSO
4
to Cu
2
O and gravimetric determination of the precipitated Cu
2
O.
The Alcolyzer

was also tested at the INRA,
Gruissan, France [
2
], which is a national institute specialized on the analysis of wines.
During the test 43 samples have been measured, among them red and white wines with low sugar concentrations, sweet wines up to 16
%v/v ethanol content and a dealcoholized wine.
The results are shown in table 2.
In the summary of the test report the French specialists come to the conclusion that “the
Alcolyzer
 by Anton Paar shows an excellent quality of analytical precision. The repeatability is comparable, if not better, than that of the distillation/density measurement method.
The simple operation of the Alcolyzer
 and the quickly available results are of clear advantage compared to distillation. Its recalibration is much more simple than that of classical NIR instruments.”
Alcolyzer
 compared to gaschromatography (GC)
Another comparative study was performed at
ETS Laboratories, NapaValley, California [
3
].
Four different NIR instruments, among them, the
Alcolyzer
 were compared to gaschromatography as reference method.
Five different wine matrices were tested on each instrument: red wines (44 samples), rosé wines
(43 samples), white wines (44 samples), turbid wines (36 samples) and sweet wines (30 samples).
The Alcolyzer

and another instrument gave the best results. However no results were obtained when very turbid samples were measured.
The correlation between the GC results and the
Alcolyzer

is shown in figure 1.
[
2
] Institut National de la Recherche Agronomique,
Institut des Produits de la Vigne, T.C. Boulet,
11430 Gruissan, France
[
3
] ETS Laboratories, Gordon Burns, 899 Adams
Street, St. Helena, CA 94574
Page 3 of 9

Application Note
Alcohol Measurement in Wine Using the Alcolyzer
Com parison betw een G C and Alcolyser (all m atrix)
7.00
R
2
= 0.9893
9.
11.
13.
15.00
00
G C Values
Figure 1 Comparison between GC and
Alcolyzer

ETS report: “The measuring data suggests that color, presence of sugar or sediment do not have a significant effect on the results.
The slope of the above correlation curve is very close to 1. This means that the Alcolyzer
 closely corresponds to the reference values provided by GC.
Table 1:
Benefits of the Anton Paar Alcolyzer

Alcohol measurements of highest precision with excellent repeatability can be performed.
Attractive price.
Comfortable and simple operation.
Large, bright display is easy to read.
Samples measured in about 1 minute.
Automatic calculation of relevant wine parameters when used in combination with
DMA 4500.
Through the menu driven software you define what is calculated, displayed and protocolled on printer and PC.
Password protection available.
Up to 100 measuring results can be stored.
Accepts standard keyboard and/or barcode reader for comfortable sample identification.
For fully automatic measurements, the
Alcolyzer can be connected to the sample changers SP-1m or SP-3m.
Alcohol content of various wines determined by distillation and with the Alcolyzer

.
Results obtained from Unione Italiana Vini, Italy (Alcolyzer in combination with SP-1m).
Sample
Alc. by distillation
[%v/v]
Alc. by
Alcolyzer

[%v/v]
Difference
(dist. - Alcolyzer

)
[%v/v]
Reducing sugar content*)
[g/l]
Red wines
Streppaticcio red 12.37 12.37 0.00 2.5 dry Selex red
Chianti red
10.40
12.44
10.37
12.41
0.03
0.03 dry
Merlot cabernet red
Primavera wine 2000
Valpolicella sup. red
Valpolicella red
Bardolino red
12.26
11.90
12.88
13.62
11.46
12.28
11.90
12.90
13.53
11.43
-0.02
0.00
-0.02
0.09
0.03 dry dry dry dry
3.6
XDLIA48A.doc
Page 4 of 9

Application Note
Alcohol Measurement in Wine Using the Alcolyzer
Sample
Alc. by distillation
[%v/v]
Alc. by
Alcolyzer
[%v/v]

Difference
(dist. - Alcolyzer

[%v/v]
)
Amarone red
Valpolicella classico red
Bardolino classico red
Amarone red
14.85
11.44
11.70
14.84
14.88
11.41
11.69
14.80
-0.03
0.03
0.01
0.04
Bertani bardolino "nouveau"red 11.81 -0.06
Reducing sugar content*)
[g/l]
5.0
4.8
1.7
5.2
3.8
Bardolino classico red
Valpolicella Valpantena red
Bardolino red
Valpolicella class. Sup. red
Valpolicella red
11.70
11.81
11.31
12.72
11.38
11.71
11.89
11.36
12.71
11.40
-0.01
-0.08
-0.05
0.01
-0.02
1.7
2.9
3.1
3.2
2.2
Valpolicella class. Sup. red
Amarone class. red
Chianti Class. Ris. red
Merlot Venezie red
Chianti red
Chianti Classico red
12.55
14.57
12.85
12.23
12.30
13.38
Valpolicella red
VdT rosso
Bardolino red
Valpolicella classico red
Merlot Grave Friuli red
Barbera d'Asti red
Valpolicella classico superiore red
Valpolicella Classico red
Barbera d’Asti red
XDLIA48A.doc
12.30
12.20
11.18
11.87
12.14
13.48
13.21
11.90
12.98
12.20
11.18
11.86
12.25
13.57
13.20
11.94
13.09
12.59
14.49
12.80
12.16
-0.04
0.08
0.05
0.07
3.3
3.9
2.8
5.1
12.20
13.28
0.10
0.10
7.5
4.1
12.06 6.9
12.25 0.05 4.9
0.00
0.00
0.01
-0.11
-0.09
0.01
-0.04
-0.11
2.4
3.9
3.3
8.4
2.8
3.0
2.8
2.5
Page 5 of 9

Application Note
Alcohol Measurement in Wine Using the Alcolyzer
Sample
Chianti red
Rosato Chiaretto VdT rosè
Alc. by distillation
[%v/v]
12.14
10.97
Alc. by
Alcolyzer
[%v/v]
12.26
11.05

Difference
(dist. - Alcolyzer

[%v/v]
-0.12
-0.08
)
Reducing sugar content*)
[g/l]
2.4
3.1
Trebbiano d'Abruzzo red 11.77 11.84 -0.07 1.6
Montepulciano d'Abruzzo red 12.27 3.6
Garda Bresciano Chiaretto
VdT red
Chianti Classico red
Barbera d’Asti red
13.18
11.35
12.54
12.62
13.12
11.33
12.59
12.65
0.06
0.02
-0.05
-0.03
1.6
8.5
2.7
3.2
Cabernet Venezie IGT red 11.21 11.21 0.00 4.2
Montepulciano d’Abruzzo red 11.82 6.0
Bardolino red 11.83 11.94 -0.11 4.3
Amarone 99 red
Castel del Monte red 99
Recioto Valpolicella class. red
“sweet”
Sparkling wines
14.30
12.34
14.36
12.45
-0.06
-0.11
12.12 11.89 0.23
4.2
2.1
93.6
Lambrusco Amabile red sparkling
Gambellara Recioto sparkling sweet
8.01
11.38
8.00
11.41
0.01
-0.03
31.5
45.2
Franciacorta "sparkling" Brut 95
Franciacorta "sparkling" Brut 97
Franciacorta "sparkling" Brut 96
Franciacorta "sparkling" Brut 96
Franciacorta "sparkling" Brut 95
Franciacorta "sparkling" Extra Dry
Franciacorta "sparkling" Extra Brut
Franciacorta "sparkling" Rose
Franciacorta "sparkling" Brut 95
Franciacorta "sparkling" Rose Demi
Sec
XDLIA48A.doc
13.00
12.06
12.46
12.53
12.39
12.19
12.14
12.87
12.95
12.09
12.46
12.51
12.33
12.16
12.08
12.76
0.05
-0.03
0.00
0.02
0.06
0.03
0.06
0.11
13.07 13.03 0.04
12.06 12.00 0.06
8.5
6.4
7.6
11.1
7.7
19.3
4.4
6.2
8.2
33.5
Page 6 of 9

Application Note
Alcohol Measurement in Wine Using the Alcolyzer
Sample
Franciacorta "sparkling" Brut 95
Franciacorta "sparkling" Brut 96
Prosecco white
VdT white
Alc. by distillation
[%v/v]
11.91
12.84
11.19
7.54
Alc. by
Alcolyzer
[%v/v]
11.88
12.82
11.11
7.55

Difference
(dist. - Alcolyzer

[%v/v]
0.03
0.02
0.08
-0.01
)
Reducing sugar content*)
[g/l]
10.3
8.5
14.8
46.6
White wines
Selex white 10.33 10.29 0.04 dry
Pinot grigio white 12.21 12.23 -0.02 dry
Chardonnay 10.40 dry
Pinot grigio white
Primavera wine 2000
Pinot grigio white
Frascati sup. white
Custoza white
Soave white
Frascati sup. white
Pinot grigio Venezie white
Orvieto Class. white
Pinot grigio Valdadige white
Pinot grigio igt Venezie white
Chardonnay Aquileia Friuli white
11.09
11.90
13.11
11.59
11.05
11.90
13.16
11.58
0.04
0.00
-0.05
0.01
11.99 11.89 0.10
11.41
12.20
11.81
12.24
12.20
11.89
12.04
11.34
12.15
11.81
12.19
12.18
11.83
11.96
0.07
0.05
0.00
0.05
0.02
0.06
0.08
8.9 dry
5.8
1.8
---
3.6
2.6
2.6
3.1
4.8
5.4
3.9
Chardonnay delle Venezie igt white 12.38 12.43 -0.05
Soave Classico Superiore white 11.75 11.79 -0.04
Terre Franciacorta white
Lugana 99 white
11.68
12.70
11.66
12.70
*) The sugar (= glucose and fructose) content was determined by titration .
0.02
0.00
3.5
5.3
1.6
1.6
XDLIA48A.doc
Page 7 of 9

Application Note
Alcohol Measurement in Wine Using the Alcolyzer
Table 2: Alcohol content of various wines determined by distillation and with the Alcolyzer

.
Results obtained from INRA, France (Alcolyzer in combination with SP-1m).
Sample
Code
Alc. by distillation
[%v/v]
Alc. by distillation
[%v/v]
Alc. by
Alcolyzer

[%v/v]
Alc. by
Alcolyzer

[%v/v]
Difference
(Average dist. - Alcolyzer

)
[%v/v]
00-461 14.17 14,15 14.30 14.30
00-462 13,97 13.93 14.10 14.09
-0.14
-0.15
00-463 10.30 10.28 10.31 10.36
00-464 11.26 11.24 11.35 11.35
00-465 14.32 14.25 14.43 14.43
00-46 13.98 13.94 14.10 14.09
-0.05
-0.10
-0.14
-0.14
00-467
00-469
12.52 12.43 12.56 12.56
11.23 11.24 11.35 11.33
00-470 11.06 11.05 11.15 11.16
00-471 11.89 11.81 11.94 11.94
00-349 15.12 15.09 15.00 14.97
00-350 15.10 15.00 14.91 14.92
00-351 14.95 14.85 14.74 14.80
00-352 15.20 15.23 15.03 15.04
V blanc 0% 0.20 0.19 0.29 0.29 viognier 14.77 14.79 14.93 14.84 viognier 13.71 13.79 13.80 13.81
Car.C45 11.18 11.20 11.23 11.24
Car.C14 13.00 13.04 13.09 13.13
-0.08
-0.10
-0.10
-0.09
0.12
0.13
0.13
0.19
-0.09
-0.05
-0.11
-0.06
-0.05
Mourv.C2 11.86 11.87 11.95 11.98
Corbières 12.07 12.07 12.11 12.11
00-400
00-401
00-402
00-403
11.28 11.29 11.33 11.33
11.28 11.21 11.29 11.30
12.54 12.57 11.61 11.63
12.30 12.33 12.37 12.35
-0.09
-0.08
-0.10
-0.04
-0.04
-0.05
-0.06
-0.04
XDLIA48A.doc
Page 8 of 9

Application Note
Alcohol Measurement in Wine Using the Alcolyzer
Sample
Code
Alc. by distillation
[%v/v]
Alc. by distillation
[%v/v]
Alc. by
Alcolyzer

[%v/v]
Alc. by
Alcolyzer
[%v/v]

(Average dist. - Alcolyzer
Muscat 15.18 15.19 15.06 15.07
Difference
[%v/v]
0.12

)
CAP1 15.06 15.06 14.90 14.91
CAP2 15.01 15.01 14.87 14.91
CAP3 15.00 15.02 14.85 14.90
M1 15.95 15.95 15.77 15.90
M2
PR1
PR2
15.86 15.91 15.86 15.86
15.34 15.38 15.32 15.33
16.01 16.01 15.84 15.94
0.15
0.12
0.13
0.11
0.03
0.03
0.12
P1
P2
P3
P4
P5
P6
P7
12.42 12.43 12.44 12.42
13.19 13.16 13.19 13.18
14.59 14.60 14.65 14.65
12.79 12.76 12.80 12.80
13.02 13.01 13.07 13.06
12.71 12.66 12.69 12.70
12.09 12.06 12.11 12.10
0.00
-0.01
-0.05
-0.02
-0.05
-0.01
-0.03
Literature
[ i
] Beneš, R., et al.: Verfahren zur spektroskopischen Bestimmung der
Konzentration von Alkoholen mit 1 bis 5
Kohlenstoffatomen; Austrian patent no.
[ ii
A323/99, PCT patent application pending
] “Alcolyzer

– A New Alcohol Meter for Wine
Analysis, G. Murer et al., 2000
[ iii
] EU regulation, No. 2676/90, 1990
[ iv
] “Alcohol Measurement Using Paar Density
Meters“, Anton Paar lab application note
XDLIA48A.doc
Page 9 of 9